This invention relates to an electronic ignition circuit that provides a high-frequency, high-voltage current wave to the ignition coil of an internal combustion engine or the like.
Conventional electronic ignition systems typically apply a pulse or spike of elevated voltage to the ignition coil primary, which provides a polar spark current to the center electrode of a spark plug. The current to the spark electrode is characterized by a single high voltage spike followed by a few progressively smaller waves of ringing current. Spark occurs only at the onset of ignition. As the piston descends during a power stroke, the combusting mixture expands adiabatically and cools. This can extinguish combustion in the combustion chamber, resulting in incomplete combustion, loss of power, and possible fouling of spark plugs and valves.
Ignition circuits typically supply polar current (usually positive-only) to the spark plugs; this produces a d.c. current flow in the plugs, which causes pitting of the spark electrodes. Also, as conventional circuits produce sparking, rather than continuous arcing, ignition and combustion are less reliable, especially in a cold engine.